Year	% of total
1990	81.76807896833222
1991	79.82075961273372
1992	76.61425696526226
1993	73.37090452074658
1994	70.50862836923434
1995	66.42518378277592
1996	65.23375846668885
1997	65.08488453599777
1998	64.99382050115157
1999	63.32951943641816
2000	63.38829031378326
2001	63.671062674117074
2002	63.41260313789607
2003	63.63404893007378
2004	62.987067560208274
2005	63.18156672257662
2006	64.80801200264878
2007	65.12969687669597
2008	65.08767982082023
2009	61.12606339100448
2010	65.84999641662075
2011	62.893899271543596
2012	58.041893586106184
2013	58.924212477990444
2014	56.71742757337246